Position-signalling devices as components of the motor drive serve for remote indication of position, or to provide information regarding the respective current position of the step switch or the like.
Such devices detect this current position electrically and process the obtained information correspondingly. The processed information then becomes the starting point and the prerequisite for the current (remote) position reading, which for instance is done optically by a lamp indicator or a dial-type instrument.
Such position-signalling devices are known from the internal company papers "Motor Antriebe MA7", (Motor Drive MA7), publication BA 40/90de-0391/2000 of the applicant. They consist of an array of signalling contacts which correspond to various operating positions of the step switch or the like and are arranged in a circle and can be switched on and off by a mobile sliding contact.
In practice numerous different variants are in use for processing the obtained information about the current position and are applicable to different situations.
Position-signalling arrays for lamp indicators switch with interruption from one signalling contact to the next. The mobile sliding contact and the signalling contacts of the contact path are connected through terminals.
Position-signalling devices for remote indication by means of dial-type instruments switch without interruption from one signalling contact to the next. For n operating positions n-1 step rheostats are built in between the signalling contacts. The beginning and the end of the contact path, as well as the mobile sliding contact are connected to terminals.
Position-signalling devices using a diode matrix deliver a coded processed signal, e.g. in BCD or Gray code.
Position-signalling devices for decimal lamp signals make possible a decimal reading.
In position-signalling devices with a break contact path the contact opens in the respective operational position.
According to the state of the art for each of the applications, special specifically designed signalling-contact arrays are made with special components tailored to the particular case. For instance in the embodiment for the remote reading by means of a dial-type instrument, as a rule a crossed coil instrument, the required individual rheostats are provided directly between the individual signalling contacts, which are swept by the sliding contact.
These known position-signalling devices, specialized for the respective type of application, have several disadvantages. On the one hand the manufacturing and the rating of the various signalling-contact arrays with their different components in various configurations are complicated and expensive. On the other hand it is not possible to adapt the position-signalling device in a flexible manner to changing requirements, which for instance could result from a short-term change of the manner in which the position indication is displayed, for instance when a lamp signal has to be replaced by a dial-type instrument with a crossed coil.